This excerpt is part of Entrepreneur.com's Second-Quarter Startup Kit, which explores the fundamentals of starting up in a wide range of industries.

In the book Start Your Own Blogging Business, the staff at Entrepreneur Press and marketing expert Jason R. Rich explain how to start a profitable business as a blogger by generating income from advertisers, subscribers, merchandisers and more. In this edited excerpt, the authors offer advice for finding a blog topic that interests both you and your potential audience.

There are many factors to consider when selecting a topic that will produce desirable profits or allow you to build a large and dedicated audience for your blog. You must consider public interest, your knowledge of the topic, its longevity, and the audience's interest in it. It's also important to look at your competition and develop a way to deliver content that's different, better, and more engaging. Start by brainstorming several possible topics you might like to use, then consider the following:

Who's the audience for the topic? As the blogger, will you be able to cater to that audience and write or produce content in a way the audience will relate to?

Does the topic have long-term appeal? Will it be relevant in six months, a year, two years or five years from now?

How large is the target audience for the topic? How will you reach the intended audience to inform them about your blog?

Will there be enough to write about the topic in the future? Off the top of your head, can you write down at least 25 things you'd blog about in future entries? Will you be able to come up with new things to blog about and keep your content fresh over the long term?

How much competition is there based on your topic? Consider other blogs, websites, magazines, newspapers, newsletters, vlogs, TV shows, radio shows, podcasts, YouTube channels, Facebook pages and other content that's out there and already targeting your audience.

What will you do differently to make your content more appealing, engaging, entertaining or interactive?

For every potential blogging topic, you can offer your opinions, experiences, commentary, news and how-to information, plus delve into subtopics or related themes. You can also focus on the controversy that surrounds a topic as a way to engage your audience.

The following are just a few general areas you might consider blogging about.

Industry-Oriented Topics. Focus on a specific industry and blog about that industry as a whole. Much of your time preparing content (blog entries) will be spent searching for industry news, following industry trends, reporting about industry breakthroughs and discussing industry gossip.

Personal Blogs. Many successful bloggers don't cover one specific topic at all, but rather, they cover a variety of topics in an entertaining manner. If you're good at making people laugh, go ahead and try your hand at a humor blog. If you're an artist, photographer, musician, songwriter, writer, poet or other creative type, you could share your work online and build a fan base.

Political Topics. Do you have an informed and insightful opinion, or an interesting way to communicate your opinions, thoughts and ideas? You might consider a political blog. And if you'd like to run a political blog but not assert your personal opinion, consider using your blog as a filter to help readers wade through all the political spin.

Hobby or Special Interest Blogs. Many people have achieved incredible success as bloggers simply by choosing a topic they were already passionate about--their hobby. In the blogosphere, you'll find entertaining, informative, gossipy and how-to blogs about all sorts of hobbies. The trick for these types of blogs is to find a niche you know about and are interested in, and then share your unique knowledge and perspective about that topic.

General Interest Blogs. Don't limit yourself to the topic areas discussed thus far. There are thousands of possibilities that have yet to be explored. You never know what will catch on or spark the interest of millions of people, especially at the wildfire pace that word-of-mouth can travel across the internet. If you have a crazy idea that might just work, go ahead and give it a shot.

When choosing what to blog about, remember to choose a topic that won't dry up. Public interest rarely stays on one topic for very long, so be sure to choose a topic that has held the interest of your target audience for a long time and will continue to do so in the future.

You must also have, or develop, a better-than-average familiarity with your chosen topic if you want readers to take you seriously. Readers won't stick around to read things they already know or that they deem irrelevant or uninteresting.

Therefore, don't choose a topic you know little or nothing about. Chances are, if you know nothing about the topic, you probably don't have much interest in it. Ideally, when people read your blog, it should be immediately obvious that not only are you an expert on the subject matter but you're also passionate about it.

Also be sure to research your competition. Find out who that competition is and how much of it actually exists. Unless you develop a unique approach, you'll do yourself a disservice by entering a topic area that's already chock-full of bloggers -- readership for that type of content may already be spread too thin, leaving all the blogs with little traffic or profit potential.

If your topic area seems crowded on first glance, remember, every topic has countless unexplored niches. Do your homework to find a topic that nobody else has done and what could work for you, based on your experience, knowledge, passion, interests and education.

Before committing yourself to one particular topic, realize that whatever topic you choose will become the focal point of your blogging life. Your interest and passion for the topic should be strong enough to sustain you through the times when you aren't sure you can bring yourself to read another article on the subject, much less write another compelling blog entry.